In a small bowl, combine warm milk, active dry yeast, and granulated sugar. Let it sit for 5-10 minutes until foamy.

In a large mixing bowl, combine remaining sugar, eggs, butter, and salt. Add activated yeast mixture, then flour and ground cinnamon. Mix until dough forms, then knead for 5-7 minutes.

Lightly oil a bowl, place kneaded dough inside, and cover to let rise for 1-1.5 hours until doubled.

Mix together brown sugar, ground cinnamon, and melted butter to prepare the filling.

Roll dough into a rectangle, spread filling evenly, roll tightly into a log, and shape into a ring.

Place shaped cake on a lined baking sheet, cover, and let rise for another 30-45 minutes.

Preheat oven to 375°F (190°C). Bake for 25-35 minutes until golden brown.

Make the glaze by whisking powdered sugar, milk or water, and vanilla until smooth.

Drizzle glaze over cooled cake and sprinkle sanding sugars. Optionally hide a small plastic baby inside.